The present invention generally relates to radio signal systems. More particularly, the invention relates to an arrangement and a method for preamplifying reception signals for a radio station, particularly for a base station, or respectively, for a radio base station of a mobile radio system, or respectively, of an access network system.
In second generation mobile radio systems, e.g., GSM (Global System for Mobile Communication) see J. Biala, Mobilfunk and Intelligente Netze, Viewe Verlag, 1195, particularly pages 57 to 92, as well as presently planned mobile radio systems (UMTS-Universal Mobile Telecommunication System) and in access network systems (see M. Reiss, Drahtlos zum Freizeichen, telecom report 18, 1995, pages 34-37), two embodiment types are realized for the design of the reception path for the preamplification of RF reception signals. Thus, in a first embodiment, a preamplifier is integrated into one rack of the base station, usually together with a multicoupling means which distributes the reception signals to a plurality of transceivers. In contrast, in a second embodiment, the preamplifier is positioned as a separate unit in the vicinity of one or more remote antennas and connected via a trunk line to a multicoupling means in the base station.
The first embodiment offers the advantage of a better maintenance opportunity on the basis of the integration in the base station of all the components essential to the processing of the reception signal. The second embodiment has the advantage of guaranteeing a particularly good reception sensitivity of the base station.
In both embodiments, due to the arrangement of the preamplifier upstream of multicoupling means and thus upstream to the transceivers of a base station, a failure of the preamplifier results in a disturbance of the reception at the base station side for the entire radio cell of the base station. Since only a very slight amplification of the reception signals occurs in the multicoupling means, the main burden of the preamplification respectively lies with the preamplifier. This arrangement enables an optimal sensitivity of the reception path, above all given a preamplifier arranged near the antenna, without increasing the demands on the high-level signal behavior of the components connected downstream in the base station. Given a failure of the preamplifier, the sensitivity of the reception path is sharply reduced due to the omission of practically the entire preamplification and to an additional attenuating of the weak reception signals by the trunk line.
Furthermore, failure is particularly critical given a preamplifier positioned near the antenna, since this preamplifier cannot always be reached and accessed easily for maintenance, repair or replacement--as may be the case in winter, given storms, or even at night, for example. Ordinarily the preamplifiers in this embodiment have a means that bridges the amplifier in the event of an error, and thus the reception path is not interrupted. Nevertheless, due to the failing preamplification, the reception path is highly insensitive for the above-mentioned reasons.
The disturbance due to the failure of the preamplifier can be partially compensated for by the use of antenna diversity, since other reception branches of the same or of a neighboring radio cell are seldom jointly affected. However, the service quality of the radio cell is considerably restricted, since qualitative benefits must be foregone due to the antenna diversity.